The present invention relates to a method and machine for pointing drills and more particularly for the grinding of drill ends to grind thereon a lip relief angle, a chisel angle and a point angle each of a selected angular dimension.
Drills or drill bits are manufactured and supplied to users with a general point configuration but without any specific point angle, lip relief angle or chisel angle. Frequently, it is the responsibility of the user to then apply these angles to the drill in accordance with the end use to which the drill is to be put. Thus, one end user may require a specific relationship of angles on the point of its drills to perform a required function while another user may require different combination of angles on its drills for an entirely different purpose.
In some instances, drills already provided by the manufacturer to the user with the required combination of angles, after a period of use, may become worn or damaged. In such instances, it is almost too costly to discard the drills. In such cases, it is less expensive, and at times easier, to regrind the drills to return them to their original condition or to change their desired end configuration. This is especially true in large manufacturing establishments where the replacement cost of drills can constitute an unusually large expense.
Many large manufacturing establishments, therefore, invest in large grinding machines that are used to regrind, grind the drills or "point" drills for reuse. In smaller factories, pointing of drills is still performed by hand by the machinist or user applying a drill gauge to check the ground surfaces of the drills to see whether they met the angular dimensions required. Also such grinding arrangements are used to regrind heavily worn drills.
In an attempt to point and repoint drills, numerous methods and machines have been devised. In the past, the procedures and machines utilized for pointing drills required complicated compound movements of the drill itself across the face of a grinding wheel so as to enable the grinding wheel to produce on the drill end the necessary point angle, lip relief angle and chisel edge angle. The machines were complicated and cumbersome requiring many moving parts that contributed to their early breakdown which resulted in their non-use and down time and subsequent loss of value to the purchaser.